Electric switch with terminal socket



Nov. 22, 1966 D. H. CAMPBELL 3,287,517

ELECTRIC SWITCH WITH TERMINAL SOCKET Filed Nov. 26. 1965 2 Sheets-Sheet 2 United States Patent 3,287,517 ELECTRIC SWITCH WITH TERMINAL SOCKET Dudley H. Campbell, St. Marys, Pa., as'signor to Stackpole Carbon Company, St. Marys, Pa., a corportion of Pennsylvania Filed Nov. 26, 1965, Ser. No. 509,806 10 Claims. (Cl. 200-50) This invention relates to electric switches, and more particularly to the arrangement of the switch terminals.

In my copending patent application, Serial No. 437,214, filed March 4, 1965, a switch is disclosed of the character with which this invention is concerned. That application shows a switch, from the back of which a straight line of terminal posts projects into a generally rectangular socket joined to the switch housing. The socket also projects laterally from one side of the housing and thereby forms an opening for a grounding terminal post secured to the side of the housing when the housing is metal. The switch housing may be provided with integral hooks that project through holes in a supporting member to hold the switch in place. It has been found desirable, however, in some cases to provide additional means for securing the switch to its support. Also, even when the switch housing is made of insulating material, it often is necessary to have a grounding terminal post in the switch socket.

It is among the objects of this invention to provide a switch of the character discussed above, which can be used with a grounding terminal post independent of the switch housing, and which can be securely anchored to a supporting member.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which FIG. 1 is a rear view of the switch;

FIG. 2 is a side view thereof;

FIG. 3 is a fragmentary section taken on the line III III of FIG. 1;

FIG. 4 is a cross section taken on the line IV-IV of FIG 2;

FIG. 5 is a fragmentary perspective section showing the switch on a different mounting; I

FIG. 6 is a perspective view of a conventional electric plug adapted to be received in the switch socket; and

FIG. 7 is a rear view of a modification.

Referring to the drawings, a switch housing has a front wall 1, a back wall or base 2, and a connecting side wall 3. The side and back walls are made of insulating material and may be integral with each other, such as being molded from a synthetic plastic. In that case, the front wall of the housing is formed by a separate dis-c. The housing may be provided with a plurality of forwardly projecting spring hooks 4 integral with its side wall and projecting through holes in a suitable metal supporting member 5 to attach the switch to it.

Mounted against the inner or front face of the housing base is a pair of laterally spaced fixed contacts 7 and 8, as shown in FIGS. 3 and 4. These contacts can be bridged by a bridging contact 9 disposed in a recess 10 in the back of an insulating switching arm 11 inside the housing. This arm may be more or less circular, but it is small enough to allow it to be swung back and forth in the housing around a post 12 on which it is mounted. The opposite ends of the post are journaled in the base and the front wall of the housing. In front of the switching arm the post is surrounded by an integral body 13 to form what is called a toggle in this art. The toggle may include a fork 14 that projects out of the housing through a slot 15 in its side wall. The outer end of the fork is adapted to receive a manually operable actuating member (not shown) for swinging the fork back and forth to open and close the switch.

The toggle is operatively connected to the switching arm in a well-known manner by a torsion spring 17 which, when the toggle is swung from one end of its path of movement to the other, snaps the arm in the opposite direction. The movement of the switching arm can be limited in the off position by the side wall of the switch housing or by other means. The arm movement in the on position is limited by engagement of bridging contact 9 with the two fixed contacts 7 and 8 as shown in FIG. 4. The ends of the spring project into a lateral projection of the toggle body and into a socket 18 in the arm.

The two fixed contacts 7 and 8 are joined to the inner ends of two rigid terminal posts 20 and 21, respectively, that extend through the housing base and project a short distance behind it. A third fixed contact-like element 22 may be mounted on the base, preferably in a straight line with the other two fixed contacts and with all three contacts equal distances apart. Nothing ever moves into and out of engagement with the third contact, so it is known as a dummy contact. This contact is on the inner end of a rigid terminal post 23 that extends outwardly through the base and is called a dummy post because it is connected to the dummy contact, but it is wired into the circuit, as will be explained later.

Another feature is that a socket for an electric plug is formed on the base of the switch, with the terminal posts inside the socket. Accordingly, a pair of side walls 25 and 26 project from the outer side of the base and are disposed parallel to the line of terminal posts. One of the side walls is on each side of the line of posts. One wall is solid, but the other is interrupted by one or more openings, as will be described. It is desirable to join the ends of the two side walls by means of end walls 27 and 28. All of these walls may be molded integrally with the switch housing. The generally rectangular socket thus formed is of such size and shape as to snugly receive a commercial electric plug 29, such as shown in FIG. 6, that is provided with a row of parallel openings 30 that will receive the three terminal posts just described. Mounted in each of the plug openings is a spring contact for engagement with the side of the adjoining post. Correct orientation or polarization of the plug in the socket can be assured by rounding at least one corner of the plug and likewise rounding the corresponding corner of the socket, as shown in FIG. 1. Such a plug, made of plastic, is sold by AMP, Inc. Opposite sides of the plug are provided with shallow recesses 32 extending across it, and the inner surfaces of the side walls of the switch socket are provided with detents 33 that will be received in those recesses when the plug is pressed into the socket. The detents help to hold the plug in place because it requires considerable effort to deform the plastic of the plug and socket sufiiciently to pull the plug away from the detents.

The dummy terminal post 23 has a wire 36 connected to it next to the housing base. To allow this wire to enter the socket, side wall 25 of the socket is provided with an access opening 37 as shown in FIG. 1. The opening may be wide enough to receive two or more wires, the second wire 38 being connected to terminal post 21 next to the dummy post. It is desirable to extend a pair of walls 39 rearwardly from the switch base and laterally away from access opening 37 to form a short channel for the two wires. The center of the channel may be provided with a divider 40, if desired, for positively separating the wires. The divider is cut away between posts 21 and 23 so that it will not prevent the plug from entering the socket. Such a switch is suitable for record players, the two wires 36 and 38 being connected to the motor that drives the turntable.

The ends of the socket side walls farthest from the dummy terminal project laterally beyond the edge of the housing base and are connected together by the end wall 27 spaced from the base. In accordance with this invention the space between this end wall and the base is filled by a block 42 that extends out into the socket some distance. The block is made of the same material as the adjoining socket walls and is integral with them. This block, the portion of divider 40 between the terminal posts, and a ledge 43 integral with end wall 28 limit the distance a plug can be inserted in the socket, as indicated in FIG. 3. The block 42 is provided with a passage 44 extending through it parallel to and in line with the terminal posts. The passage is outside of the periphery of the switch housing and is designed for receiving a grounding terminal post that is connected to the metal support for the switch. To permit the passage to accommodate either of two different types of grounding posts, it has a substantially rectangular shape extending crosswise of the socket, and the central areas of the side walls of the passage are concave and form segments of a common cylinder, as shown in FIGS. 1 and 5.

One type of grounding terminal post is a threaded metal screw 45 of special form, which also i used for locking the switch against its support so that it cannot be dislodged in case hooks 4 do not hold. This screw is long enough to extend through metal support and socket passage 44 and to project into the socket beyond block 42 as far as the other terminal posts. The free end portion of the screw inside the socket is smooth and the same diameter as the other posts. It will be received in the fourth opening of plug 29. The threaded portion of the screw is screwed into passage 44. The curved-areas of the passage may be prethreaded or, if desired, a selftapping screw may be used as shown. Thus, the screw fastens the switch to its support and also forms a terminal post grounded to the support. To prevent the act of tightening the screw from tilting the switch, due to the screw being outside of the switch housing, the adjoining end wall 27 of the socket may be provided with an extension 46 that extends along the screw and into engagernent with the support 5. As shown in FIG. 3, the switch and socket wall extension therefore engage the support on opposite sides of the screw and cannot be tilted by the screw.

If a grounding terminal post is not desired, a shorter screw can be used, in which case its only function will be to lock the switch on its support.

It also is desirable to be able to mount this switch on a certain kind of metal support 48 that is provided with an integral grounding post 49, as shown in FIG. 5. The base portion of the post is rectangular and of a size to fill the entire socket passage 44. To mount the switch in place, the free end of the grounding post is inserted in the front end of the socket passage and then the switch is moved toward the supporting member until its hooks 4 snap into place. The grounding post fills the socket passage, but it has a more or less cylindrical outer end portion that projects into the socket from block 42. There then will be four terminal posts in line and equally spaced for connection to the type of plug previously described herein.

In the modification shown in FIG. 7, one side wall 51 of the switch socket opens out into a channel 52 extending laterally away from that wall as in FIG. 1, but in addition the same side wall has a second access opening 53 therein so that a wire can be brought into the socket from its side and attached to terminal post 54. A channel 55 for the wire is formed between laterally projecting wall 56 and another lateral wall 57 at the opposite side of opening 53. A cut down portion 5-8 of wall 56 may extend across the socket between two terminal posts to better separate the wires that are connected to those posts.

According to the provisions of the patent statutes, I have explained the principle of my invention and have illustrated and described what I now consider to repre sent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims,

the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. An electric switch comprising a housing having an insulating base, a pair of fixed contact in the housing mounted on the base, a bridging contact movably disposed in the housing, manually operable means for moving the bridging contact into and out of engagement with the fixed contacts, terminal posts connected to said fixed contacts and projecting from the outer side of the base, a pair of side walls projecting from the outer side of the base parallel to said posts between them and also projecting laterally away from one edge of said base, and an end wall connecting the outer ends of the projecting side walls and spaced from said base, said walls forming a socket, the socket being provided between said end wall and base with an internal insulating block integral therewith and having a passage therethrough parallel to and in line with said terminal posts, the passage being formed for removably receiving a grounding terminal post connected to a metal support for the switch and extending into the socket from said passage, and said socket being adapted to receive a separate electric plug provided with a row of openings for receiving the terminal posts.

2. An electric switch as defined in claim 1, including a dummy terminal post projecting from the outer side of said base at the end of the socket opposite to said passage, the dummy post being in line with the other terminal posts, an end wall connecting the ends of said side walls adjacent the dummy post, and one of said side walls being provided with an access opening for wires to be attached to said dummy post and the terminal post next to it.

3. An electric switch as defined in claim 1, in which said block passage is substantially rectangular for sliding said housing is provided with positioning lugs for hold- I ing it in a predetermined position on its support.

7. An electric switch as defined in claim 1, including a dummy terminal post projecting from the outer side of said base at the end of the socket opposite to said passage, the dummy post being in line with the other terminal posts, an end wall connecting the ends of said side walls adjacent the dummy post, and one of said side walls being provided with an access opening for wires to be attached to said dummy post and the terminal post next to it, said one side wall also being provided with a second access opening for a wire to be attached to the terminal post next to said passage.

8. The combination with a metal support, of an electric switch engaging the support and comprising a housing having an insulating 'base spaced from the support, a pair of fixed contacts in the housing mounted on the base, a bridging contact movably disposed in the housing, manually operable means for moving the bridging contact into and out of engagement with the fixed contacts, terminal posts connected to said fixed contacts and projecting from the outer side of the base, a pair of side walls projecting from the outer side of the base parallel to said posts between them and also projecting laterally away from one edge of said base, and an end wall connecting the outer ends of the projecting side walls and spaced from said base, said walls forming a socket, the socket being provided between said end wall and base with an internal insulating block integral therewith and having a passage therethrough parallel to and in line with said terminal posts, and a headed metal screw extending through said support and screwed into said passage to hold the switch firmly against the support, the screw having a smooth end portion projecting into the socket from said passage to form a grounding terminal :post, said socket being adapted to receive a separate electric plug provided with a rOW of openings for receiving the terminal posts.

9. The combination recited in claim 8, including an integral extension of said end wall engaging said support beside the screw.

10. The combination recited in claim 8, in which said support is provided with a plurality of openings therethrough, and the adjoining side of said switch housing is provided with positioning lugs extending through said openings and then laterally to lock the lugs in the openings.

No references cited.

ROBERT K. SCHAEFER, Primary Examiner.

J. R. SCOTT, Assistant Examiner. 

1. AN ELECTRIC SWITCH COMPRISING A HOUSING HAVING AN INSULATING BASE, A PAIR OF FIXED CONTACTS IN THE HOUSING MOUNTED ON THE BASE, A BRIDGING CONTACT MOVABLY DISPOSED IN THE HOUSING, MANUALLY OPERABLE MEANS FOR MOVING THE BRIDGING CONTACT INTO AND OUT OF ENGAGEMENT WITH THE FIXED CONTACTS, TERMINAL POSTS CONNECTED TO SAID FIXED CONTACTS AND PROJECTING FROM THE OUTER SIDE OF THE BASE, A PAIR OF SIDE WALLS PROJECTING FROM THE OUTER SIDE OF THE BASE PARALLEL TO SAID POSTS BETWEEN THEM AND ALSO PROJECTING LATERALLY AWAY FROM ONE EDGE OF SAID BASE, AND AN END WALL CONNECTING THE OUTER ENDS OF THE PROJECTING SIDE WALLS AND SPACED FROM SAID BASE, SAID WALLS FORMING A SOCKET, THE SOCKET BEING PROVIDED BETWEEN SAID END WALL AND BASE WITH AN INTERNAL INSULATING BLOCK INTEGRAL THERE- 